package com.lagou.edu.filter;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * 定义全局过滤器，会对所有路由生效
 */
@Slf4j
@Component  // 让容器扫描到，等同于注册了
@RefreshScope
public class LimitFilter implements GlobalFilter, Ordered {


  @Value("${ip.limit.minute}")
  private Integer minute;
  @Value("${ip.limit.max}")
  private Integer max;


  private Map<Long, Map<String, AtomicInteger>> map = new HashMap<>();

  @Override
  public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    // 思路：获取客户端ip，判断是否在黑名单中，在的话就拒绝访问，不在的话就放行
    // 从上下文中取出request和response对象
    ServerHttpRequest request = exchange.getRequest();
    ServerHttpResponse response = exchange.getResponse();
    // 从request对象中获取客户端ip
    String clientIp = request.getRemoteAddress().getHostString();

    String url = request.getURI().getPath();

    if (!url.contains("/user/register")){
      //只对注册限制
      return chain.filter(exchange);
    }


    long min = (System.currentTimeMillis() / 1000 / 60);

    if (map.get(min) == null) {
      map.clear();
      Map h = new HashMap<>();
      h.put(clientIp, new AtomicInteger(1));
      map.put(min,h);
    } else {
      Map<String, AtomicInteger> ip = map.get(min);
      ip.computeIfAbsent(clientIp, (str) -> new AtomicInteger(0));

      if (ip.get(clientIp).incrementAndGet() > max / minute) {
        response.setStatusCode(HttpStatus.SEE_OTHER); // 状态码
        String data = "REQUEST LIMIT ";
        DataBuffer wrap = response.bufferFactory().wrap(data.getBytes());
        return response.writeWith(Mono.just(wrap));
      }
    }
    // 合法请求，放行，执行后续的过滤器
    return chain.filter(exchange);
  }


  /**
   * 返回值表示当前过滤器的顺序(优先级)，数值越小，优先级越高
   *
   * @return
   */
  @Override
  public int getOrder() {
    return 0;
  }
}
